1. Field of the Invention
The present invention relates to poles having solar cells and an electric device, such as a street lamp or like lighting device, public sign, electric clock or communications device, attached thereto.
2. Description of the Related Art
Independent power source systems generally in outdoor use for supplying electric energy, for example, to lighting devices for street lamps comprise solar cells which are invariably installed in a south-facing location where sunshine is available and which are attached to the top of a pole as inclined obliquely upward at an angle of about 45 deg with a horizontal plane so as to absorb solar energy most efficiently. The electric energy generated is charged into a storage device with consideration given to the average duration of sunshine per day. The storage device used in this case has a capacity to store an amount of electric energy corresponding to 5 to 30 days to compensate for the days on which sunshine is unavailable since the storage device is not fully chargeable on rainy or cloudy days.
With such conventional outdoor powder source systems, the place where the solar cells are installed is inevitably limited to a south-facing location where sunshine is available, and no consideration is given to compensate for operation in the shade.
The solar cell arrangement is conventionally installed as inclined obliquely upward at an angle of about 45 deg with a horizontal plane and therefore permits deposition, for example, of bird droppings on its surface, failing to charge the storage device. The solar cell arrangement thus inclined further is covered with snow during winter in a cold climate and likely to become incapable of charging the storage device. Additionally, the solar cells need to have a completely water-tight structure to prevent rainwater from penetrating into the cell while the water flows over the inclined surface thereof. Because the solar cells are attached as inclined to the top of the pole, the pole equipped with the cells has a poor balance, is prone to falling down as a result of the wind or an earthquake and remains to be improved in safety.
Furthermore, it has been necessary to use a large storage device having a capacity for storing an amount of electric energy corresponding to 5 to 30 days to compensate for the lack of sunshine. This renders the pole costly and heavy, entailing the problem that the casing provided separately from the main body of the pole for housing the storage device requires an increased space for the installation of the casing.